A friendly user reported a failed backup, and on close inspection it turned out that link-backup was attempting to backup atypical file types such as pipes, sockets, and devices. Now link-backup knows how to ignore those types of files.

Added --ssh-C on request to compress the transfer stream. If you're mainly backing up already compressed files such as pictures and music, --ssh-C is likely not to be a win. For other types of files, it'll save some bandwidth.

Added --ssh-i and ssh-p on request. Good options, thanks for the suggestions and code!